/**
 * Luminosity
 * http://en.wikipedia.org/wiki/Luminosity
 */

THREE.LuminosityShader = {

	uniforms: {

		'tDiffuse': { value: null }

	},

	vertexShader: [

		'varying vec2 vUv;',

		'void main() {',

		'	vUv = uv;',

		'	gl_Position = projectionMatrix * modelViewMatrix * vec4( position, 1.0 );',

		'}'

	].join( '\n' ),

	fragmentShader: [

		'#include <common>',

		'uniform sampler2D tDiffuse;',

		'varying vec2 vUv;',

		'void main() {',

		'	vec4 texel = texture2D( tDiffuse, vUv );',

		'	float l = linearToRelativeLuminance( texel.rgb );',

		'	gl_FragColor = vec4( l, l, l, texel.w );',

		'}'

	].join( '\n' )

};
